Fire fighting apparatus for floating roof and petro chemical storage tanks are well known and have been in use for many years. For example, a U.S. Patent of Flandre, U.S. Pat. No. 4,893,681 discloses a Firefighting Installation For Floating Roof Hydrocarbon Storage Tanks. As disclosed the installation includes a series of vertical pipes disposed regularly around the tank. A sprayer at the top of each pipe is adapted to form a flat jet of extinguishing foam directed towards the interior of the tank along its inside wall. A pressurized water supply is connected to the pipes through an emulsifying agent feed system. An air injector on each pipe near the sprayer favors the formation of the foam. Each sprayer includes two nozzles set at an angle to each other and directed towards the floating roof. Each nozzle incorporates a longitudinal slot in its end portion opposite the free end and facing towards the floating roof.
A Method and Means for Extinguishing Tank Fires is also disclosed in a U.S. Pat. No. 5,377,765 of Kaylor. As disclosed therein, a method and means wherein fires in tanks storing combustible liquids are extinguished by injecting a mixture of water, a foam-forming concentrate and an inert gas into the tank at a point below the surface of the stored liquid forming an up-welling foam column which explodes upon the liquid surface and spreads across that surface to extinguish the fire and prevent its reigniting.
A further approach to a method for extinguishing tank fires is disclosed in a further patent of Kaylor, U.S. Pat. No. 5,464,065. This patent discloses a Method for Extinguishing Tank Fires wherein the fires in tanks storing combustible liquids are extinguished using water from a settled layer at the tank bottom to form a foam that is transported to the top of the combustible liquid by the lifting action of an inert gas stream introduced into the tank at a location below the liquid surface. A stream of water is removed from the tank, mixed with a foam-forming concentrate, merged with a flowing stream of inert gas, and circulated back to the tank at a point below the surface of the stored liquid to form an upwelling foam column which explodes upon the liquid surface and spreads across that surface to extinguish the fire and prevent its reigniting.
Finally, a U.S. Patent of Sharma et al, U.S. Pat. No. 5,573,068 discloses an apparatus for extinguishing fires in oil storage tanks that uses either foam or dry chemical powder, or both as the extinguishant. The device comprises at least one annular pipe ring arranged in a horizontal plane just above the bottom of the storage tank and connected to a supply of extinguishant. When more than one ring is used, the rings are concentrically and equidistantly arranged with the outermost ring connected to the supply of extinguishant. The pipes have two or more diametrically connected cross-members. Vertically extending discharge pipes are situated at the junctions of the pipe rings and cross-members. The top ends of the discharge pipes are above the highest level of flammable liquid in the storage tank and are equipped with discharge nozzles. The discharge nozzles provide for uniform discharge of the extinguishant onto the surface of the flammable liquid held in the storage tank.
Notwithstanding the above, it is presently believed that there is a need and a potential commercial market for a fire extinguishing system for oil storage tanks and the like in accordance with the present invention. There should be a demand and a commercial market for such systems because the systems and apparatus have the advantage of quickly removing a majority of the flammable material from the proximity of the fire and providing safe storage until the fire is extinguished.